The electroplating industry generates wastewater containing a variety of heavy metals which potentially contaminate water ecosystems. The available and well-known electroplating wastewater treatments are considered as an expensive and less effective method, therefore phytoremediation was used as an alternative friendly solution. This study aims to evaluate the uptake and elimination rate of heavy metals by vetiver (Chrysopogon zizanoides L.) on metal-polluted water. Vetiver was planted in artificial electroplating wastewater containing different levels (low, medium, high) of chromium (Cr) and nickel (Ni). Water, roots, and shoots were collected periodically to determine Cr and Ni contents using Atomic Absorption Spectrometry (AAS). Metal accumulation and elimination rate, Bioconcentration Factor (BCF), Biological Absorption Coefficient (BAC), and Translocation Factor (TF) were calculated to evaluate plant’s effectiveness in metal remediation processes. The results showed that vetiver (C. zizanoides L.) was able to remove 61.10% Cr and 95.65% Ni on metal-contaminated water. The highest uptake rates for Cr and Ni are 127.21 mg/kg/day and 15.60 mg/kg/day respectively, while the elimination rates for Cr and Ni tend to slow 1.09 mg/kg/day and 12.24 mg/kg/day respectively. Vetiver BCF, BAC, and TF values on Cr and Ni contaminated water were greater than 1, which indicates that vetiver work through phytoextraction and phytostabilization to treat metals. The findings showed that vetiver has promise as a phytoremediation agent thus providing implication for electroplating wastewater treatment.

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Renewable energy plays an important role for a sustainable future and the use of microalgae Nannochloropsis sp., as a potential source of biofuel due to its high lipid content, makes a good option. The nutrient found in the growth medium of microalgae have been found to affect cell synthesis, lipid synthesis, as well as its fatty acid profile. This study was conducted to observe the effects of the N-P concentration utilizing multistage feeding on the performance of Nannochloropsis sp. Sodium bicarbonate, urea, and sodium dihydrogen phosphate monohydrate were used as sources of C, N, and P for the microalgae. The nutrient feeding needed was calculated based on a molecular formula of microalgae(CO0.48H1.83N0.11P0.01) with a production target 1g.L-1 cell biomass. Element C is an iso-molar. The concentration of N- P varies: corresponding to the mol-fraction of the microalgae cell (as a control) and 10% excess. There were four levels of treatment: A (U0P0); B (U10P0); C (U0P10); and D (U10P10) with three replicants in the batch culture system. Nutrient feeding was conducted in three stages: I (40%); II (30%);and III (30%) and incubated in a neutral environment. Nannochloropsis sp. was able to grow well at a temperature of 24–35°C and an acidity level (pH) of 9.0–10.5. The culture (on the 21st day) produced DCW 0.93; 1.04; 0.86;1.12g.L-1, Chlorophyll-a 7.08; 7.62; 4.64; 6.85% DC, lipid 19.2; 15.5; 27.3; and 21.6% DC for treatments A; B;C; and D, respectively.The maximum lipid level resulted in an N deficiency and a P surplus (C). The lipids of the Nannochloropsis sp. composed of 66.0–81.1% saturated fatty acid which is suitable to be used as a biofuel.